Open-source technologies and auxiliary electrodes for microbial fuel cell optimization
Sánchez, Carlos
Sánchez, Carlos
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Publication Date
2022-06-10
Type
Thesis
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Abstract
The purpose of this PhD thesis was to study direct waste-to-electricity transformations using microbial fuel cells (MFC) to obtain electricity as a byproduct of waste degradation. The extensive study of the literature on the topic and the acknowledgement of the present limitations of MFCs derived into a specific set of objectives: i) how to improve the analysis of MFC systems and ii) how to make the electronic tools and software required for the analysis of microbial electrochemical technologies (MET) more available. For the first objective, this work focused on the comparison of the electrochemical parameters that distinguish a polarized electrode from an open-circuit (non-polarized) electrode. The polarized electrodes or closed circuit, in which current flows, and the "novel" open-circuit (OC) auxiliary electrode in which current does not flow. This highlighted the valuable information that can be obtained from the OC auxiliary electrode in relation to the bulk conditions of the electrolyte (Chapter 3) and by the clear visualization of catalytic activity comparing polarized vs non-polarized electrodes (Chapter 6). The OC auxiliary electrode served to troubleshoot MFC anodic conditions due to sudden changes in potential. It also allowed identifying redox peaks caused by polarization during cyclic voltammetry (CV) sweeps. Moreover, the OC auxiliary electrode served to detect interpretable changes in electrochemical impedance spectroscopy (EIS) results which could not be detected easyly otherwise. The second objective was accomplished by showing that open-source hardware electronics and programming platforms are powerful ways to facilitate the required tools for appropriate control of microbial-electrode interactions. This was highlighted by the low cost that could be achieved for some necessary laboratory infrastructure (Chapter 4) and by the improved data analysis workflow achieved with the open-source software (Chapter 5). The use of open source technologies in relation to MET could allow MET research, often expensive, to be investigated in laboratories with lower budgets, improving the overall understanding and applicability of these systems. Overall, this PhD work provides a set of observations and tools that can guide improved experimental set-ups to give a better understanding of MFC and MET.
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NUI Galway